Electrocatalytic Application of Girard's Reagent T to Simultaneous Determination of Furaldehydes in Pharmaceutical and Food Matrices by Highly Sensitive Voltammetric Methods

Sensitive and precise voltammetric methods for the determination of trace amounts of furaldehydes, mainly as furfural (F) and 5‐hydroxymethyl‐2‐furaldehyde (HMF), in foods, pharmaceutical and other matrices is described. Determination of total furaldehyde at <μg g^?1 levels in alkaline buffered aqueous media was individually investigated. By the use of ordinary SWV and adsorptive square wave stripping voltammetry (Ad‐SWSV), the detection limits for determination of F and HMF found to be 400 and 10 ng g^?1, respectively. At a 1.0 μg g^?1 level of furfural in sample, the relative standard deviation (n=4) was 2.79%. The application of Ad‐SWSV to the determination of F and HMF, after their in situ derivatization with trimethylaminoacetohydrazide chloride (Girard's reagent T) at a static mercury drop electrode (SMDE) in NH₃‐NH₄Cl buffer of pH 9.5, resulted in a limit of detection of 10 ng g^?1 for the resolved peaks of HMF and F. The results obtained by the proposed method for the real samples were compared with the corresponding results from UV‐spectrophotometry and HPLC experiments in various matrices.     

Preparation,Characterization and Electrochemical Application of Graphene‐metallic Nanocomposites

Three different Graphene‐Metallic (Graphene‐Me) nanocomposites – Graphene‐Silver (Graphene‐Ag), Graphene‐Gold (Graphene‐Au) and Graphene‐Platinum (Graphene‐Pt) nanocomposites – were prepared and characterized. The electrochemical performances of these nanocomposites were tested by incorporating them with glassy carbon paste electrode (GCPE) and used them in biofuel cells (BFC) and as amperometric xanthine biosensor transducers. Present work contains the first application of Graphene‐Au and Graphene‐Ag nanocomposite in BFCs and also first application of these Graphene‐Me nanocomposites in xanthine biosensors. Considering BFC, power and current densities were calculated as 2.03 µW cm^?2 and 167.46 µA cm^?2 for the plain BFC, 3.39 µW cm^?2 and 182.53 µA cm^?2 for Graphene‐Ag, 4.43 µW cm^?2 and 230.15 µA cm^?2 for Grapehene‐Au and 6.23 µW cm^?2 and 295.23 µA cm^?2 for Graphene‐Pt nanocomposite included BFCs respectively. For the amperometric xanthine biosensor linear ranges were obtained in the concentration range between 5 µM and 50 µM with the RSD (n=3 for 30 µM xanthine) value of 4.28 % for plain xanthine biosensor, 3 µM and 50 µM with the RSD (n=3 for 30 µM xanthine) value of 9.37 % for Graphene‐Ag, 5 µM to 20 µM with the RSD (n=3 for 5 µM xanthine) value of 9.00 % and 30 µM to 70 µM with the RSD (n=3 for 30 µM xanthine) value of 8.80 % for Grapehene‐Au and 1 µM and 70 with the the RSD (n=3 for 30 µM xanthine) value of 2.59 % for Grapehene‐Pt based xanthine biosensors respectively.     

Effect of Different Ionic Liquids on 5-Hydroxymethylfurfural Preparation from Glucose in DMA over AlCl3: Experimental and Theoretical Study

In this work, effect of different ionic liquids (ILs) on 5‐hydroxymethylfurfural (HMF) preparation from glucose in N,N‐dimethylacetamide (DMA) over AlCl₃ was revealed by a combined experimental and computational study. ILs used as cocatalysts in this work included N‐methyl‐2‐pyrrolidone hydrogen sulfate ([NMP]HSO₄), N‐methyl‐2‐pyrrolidone methyl sulfate ([NMP]CH₃SO₃), N‐methyl‐2‐pyrrolidone chlorine ([NMP]Cl) and N‐methyl‐2‐pyrrolidone bromide ([NMP]Br) which were endowed with the same cation but different anions. According to the conclusion that fructose was intermediate product from glucose to HMF, we found fructose was transformed to more by‐products by [NMP]HSO₄, making HMF yield decline significantly when glucose was treated as substrate. Neither glucose nor fructose could be converted by [NMP]CH₃SO₃ efficiently, leading to its no influence on glucose conversion to HMF. [NMP]Br had a higher selectivity for HMF from fructose than [NMP]Cl and AlCl₃. Besides, Al³⁺ preferred to combine with Br^?, slightly decreasing both the overall free energy barrier for glucose isomerization and activation barrier for H‐shift at 393.15 K. So a high HMF yield of 57% was obtained from glucose catalyzed by AlCl₃ together with [NMP]Br under mild conditions.     

Electrochemical Detection of Methimazole by Capillary Electrophoresis at a Carbon Fiber Microdisk Electrode

We developed a sensitive, simple and low cost method to determine methimazole based on capillary electrophoresis with electrochemical detection (CE‐EC) at a carbon fiber microdisk electrode (CFE). We investigated the effects of detection potential, the concentration and pH value of the phosphate buffer, and injection time as well as separation voltage on the detection of methimazole. Under the optimized conditions: the detection potential at 1.30 V, 10 mmol/L phosphate buffer (pH 7.0), injection time 30 s at a height of 20 centimeter and separation voltage at 15 kV, the linear range was obtained from 1.0×10^?7 to 2.0×10^?4 mol/L, covering 3 orders of magnitude with a correlation coefficient of 0.9995. The LOD (S/N=3) obtained was 5.0×10^?8 mol/L. The RSD of migration time and peak current for 2.0×10^?4 mol/L methimazole was 1.04% and 1.54% (n=10), respectively. The method was also used to analyze methimazole tablets and human urine sample.     

Miniaturized flow-injection-analysis (μFIA) system with on-line chemiluminescence detection based on the luminol-hypochlorite reaction for the determination of ammonium in river water

A miniaturized flow-injection-analysis system constructed from glass and polydimethylsiloxane was employed for the determination of ammonium in river water. The sample was filtered and delivered to the reactor chip electro-osmotically using a disposable fritted capillary, while reagents were delivered to the system by gravity. Ammonia was mixed with the hypochlorite, to form a monochloramine. Once the alkaline luminol (3-aminophthalhydrazide) was delivered to the system, it was oxidized by the unconsumed hypochlorite emitting a bright blue light (λ _max?～?440?nm) that was detected using a miniaturized photomultiplier tube (PMT) located directly under the chip. The calibration model for ammonium standards was linear up to 0.1?µg?mL^?1 (y?=??8.96x?+?1.02; correlation coefficient, r ²?=?0.9715) over a working range of 0.0–0.5?µg?mL^?1. A detection limit of 10?±?6?µg?mL^?1 was achieved with a precision value of (RSD ≤ 6.4%), for n?=?5. A direct and standard addition method were used to determine the concentration of ammonium in a river-water sample (from the Humber Estuary, UK) which was found to be 0.075?±?0.005?µg?mL^?1, with a precision value of (RSD?≤?3.7%), for n?=?9. The results obtained showed good agreement with the average concentration 0.065?µg?mL^?1 (provided by the local environmental agency), for the analysis of ammonia at different sample points on the estuary.     

Comparison of an HPTLC method with the Reflectoquant assay for rapid determination of 5-hydroxymethylfurfural in honey

5-Hydroxymethylfurfural (HMF) was analyzed in 17 botanical varieties of honey from 12 countries. A recently developed high-performance thin-layer chromatographic (HPTLC) method was limited because of increased matrix effects at higher honey sample loading. Therefore, the method was modified to achieve higher sensitivity and eliminate matrix interference by use of rectangular application combined with a focusing step. The HPTLC results were compared with results from the new spectrophotometric Reflectoquant hydroxymethylfurfural assay. Both methods had quantification limits of 4 mg kg^?1 and were suitable for rapid quantification of HMF in honey at the strictest regulated level of 15 mg kg^?1. Comparable results were obtained for the 17 honey samples, with a mean deviation of 2.9 mg kg^?1 (15 %). The optimized HPTLC method was proved to be highly matrix-robust and was validated for the 17 different honey matrices (correlation coefficients ≥0.9994 (n?=?6), mean intra-day precision 3.2 % (n?=?3 within a plate; n?=?2 repeated within a day), mean inter-day precision 3.7 % (n?=?3), mean reproducibility over the whole procedure including sample preparation 4.1 % (n?=?2), and mean recovery 106.9 % (n?=?5 different concentrations; n?=?4 different honey matrices). Recovery for a range of different application volumes, and thus for different honey matrix loading, differed by only ≤4.2 %. HMF results when calculated by use of external calibration and by use of the standard addition method varied by 8.8 %. Both revealed that any matrix effect was minor and that the original matrix interference problem was successfully solved.

Speciation of Organotin Compounds by Capillary Electrophoresis Coupled with Hydride Generation Atomic Fluorescence Spectrometry

Abstract

Capillary electrophoresis (CE) coupled with hydride generation atomic fluorescence spectrometry (HG‐AFS) was developed for the speciation analysis of organotin compounds. The four organotin cations of trimethyltin (TMT), monobutyltin (MBT), dibutyltin (DBT), and tributyltin (TBT) were completely separated by CE in a 50 cm×75 µm i.d. fused‐silica capillary at 15 kV and using a mixture of 50 mmol l^?1 H₃BO₃?50 mmol l^?1 Tris‐5% v/v methanol (pH 7.10) as electrolyte. 0.008 mmol l^?1 cetyltrimethylammonium bromide (CTAB) added to the electrolyte suppressed the adsorption of the organotin cations on the inner wall of capillary. The generated hydride species were detected on‐line with AFS. The precisions (RSD, n=5) were in the range of 1.7–3.1% for migration time and 3.8–4.7% for peak area response for the four organotin species. The detection limits ranged from 1–10 µmol l^?1 (as Sn).     

Validation of UV Spectrophotometric Method for Fexofenadine Hydrochloride in Pharmaceutical Formulations and Comparison with HPLC

Abstract

A simple, reproducible, accurate, and effective spectrophotometric method was developed and validated for the quantitation of the antihistamine fexofenadine in capsules and coated tablets. Ethanol was used as solvent and the absorbance at the wavelength of 220 nm was employed to the quantitation of the drug. The method validation was fulfilled through the evaluation of the analytical parameters of linearity, precision, accuracy, limits of detection, and quantitation and specificity. The method was linear (r=0.9999) at concentrations ranging from 8.0 to 20.0 µg ml^?1, precise (RSD intra‐day=0.29; 0.18; 0.39; RSD inter‐day=0.12 for capsules and RSD intra‐day=0.13; 0.16; 0.13; RSD inter‐day=0.13 for coated tablets), accurate (percentage recovery=99.97% for capsules and 100.51% for tablets), sensitive (limits of detection and quantitation of 0.10 and 0.29 µg ml^?1, respectively) and specific. The method was compared to a high performance liquid chromatography (HPLC) method, which was previously developed to the same drug. The results showed no significant difference between the methods in fexofenadine hydrochloride quantitation.     

Determination of phosphate in freshwater samples by flow-injection with lucigenin chemiluminescence

Lucigenin chemiluminescence (CL) in conjunction with flow-injection analysis (FIA) is used for the determination of phosphate in freshwater samples. The procedure is based on the formation of molybdophosphoric heteropoly acid (MoP–HPA) by the reaction of phosphate and ammonium molybdate under acidic conditions. CL emission was observed as a result of oxidation of lucigenin in aqueous sodium hydroxide solution in the presence of MoP–HPA. Calibration was linear up to 500?µg?L^?1 (r ^2?=?0.9998; n?=?8), with a detection limit (S/N?=?3) of 0.95?µg?L^?1. An injection throughput of 120 h^?1, and relative standard deviation (RSD; n?=?4) of 1.3–3.2% were achieved in the concentration range studied. An on-line chelating column was used to remove interfering cations. The method was applied to freshwater samples, and the results (51?±?1.0 – 107?±?2.0?µg?L^?1) did not differ significantly from results obtained using a spectrophotometric method (52.5?±?1.0 – 102?±?2.0?µg?L^?1) at 95% confidence level (t-test).     

Determination of carbaryl by flow injection with luminol chemiluminescence inhibition detection

A flow-injection procedure is described for the determination of carbaryl based on its inhibition effect on luminol-cobalt(II) chemiluminescence reaction in alkaline medium in the presence of hydrogen peroxide. The calibration data over the range 5.0?×?10^?7 to 20?×?10^?6?M give a correlation coefficient (r ²) of 0.9972 with relative standard deviations (RSD; n?=?4) in the range of 1.0–2.1% with a limit of detection (3?×?blank noise) of 2.37?×?10^?7?M for carbaryl. The sample throughput was 120?h^?1. The effects of some carbamates, anions, and cations were studied on luminol CL system for carbaryl determination. The proposed method has been applied to determine carbaryl in natural waters.     

Solid Substrate Room Temperature Phosphorimetry for the Determination of Trace Mercury Based on the Reaction between Alkaline Phosphatase and Mercury Using Triton X-100 as a Sensitizer

A new solid substrate room temperature phosphorimetry (SSRTP) for the determination of trace mercury has been established, using Triton X‐100 as a sensitizer. The regression equation of working curve was ΔI_p=11.40m(Hg²⁺)+1.569 (ag·spot^?1, n=6, ΔI_p=I_p1?I_p2, I_p1 and I_p2 referred to the phosphorescence intensity of the blank reagent and the test solution, respectively), and correlation coefficient (r) was 0.9984. The RSD valus of the determination of 0.016 and 8.0 ag·spot^?1 Hg²⁺ were 4.1% and 1.7% (n=8), respectively, indicating that the method had good repeatability. The limit of detection (LOD) calculated by 3Sb/k was 7.0 zg·spot^?1 Hg²⁺ (corresponding concentration: 1.8×10^?17 g·mL^?1, Sb=0.025, n=11). This method has high sensitivity, selectivity and precision, which was applied to determination of trace mercury in water samples with the result being agreed very well with that of dithizone extraction spectrophotometry.     

Flow-injection determination of total iron in freshwater samples with neutralisation chemiluminescence

A flow-injection chemiluminescence method has been established for the determination of total iron in freshwater samples. The enhanced chemiluminescence emission was caused by the iron(II) from the neutralisation reaction of hydrochloric acid and sodium hydroxide without the use of any chemiluminescent reagent. The calibration graph was linear in the concentration range of 2.8–560 µg L^?1 (r ² = 0.9983, n = 8), with relative standard deviation (RSD; n = 4) in the range of 0.8–2.6%. The limit of detection (S/N = 3) was 0.56 µg L^?1 with injection throughput of 180 h^?1. The effect of common anions and cations were studied over their environmentally relevant concentrations in freshwaters. The method was successfully applied to determine total iron in freshwater samples. Iron(III) was reduced to iron(II) by using hydroxylammonium chloride. The proposed method was compared with spectrophotometric method and there was no significant difference between the two methods at the 95% confidence level (t-test). Analysis of river water (certified reference material SLRS-4) for iron(II), after reduction of iron(III) with hydroxylammonium chloride, gave good results (2.17 ± 0.22 µM compared with the certificate value of 1.85 ± 0.1 µM).     

Electrochemiluminescence of SDBS‐Ru(bpy)32+‐CPM System and Its Application

When the concentration of dodecyl benzene sulfonic acid sodium salt (SDBS) is 0.7 mmol·L^?1, the electrochemical and electrochemiluminescence (ECL) intensity of Ru(bpy)₃²⁺‐chlorpheniramine maleate (CPM) system at the Au electrode were studied. The results showed that compared with the absence of SDBS, enhancement of the ECL intensity was 14‐fold at Au electrode. Base on this, an ECL method was established for efficient and simple determination of CPM at Au electrode. Under the optimum experimental condition, the enhanced ECL intensities had good linear relationship with the concentration of CPM in the range of 1.0×10^?4–1.0×10^?7 mol·L^?1, and a linear regression equation was obtained as follows: I (counts)=48.805×10⁶c+394.03 (r=0.9975), the detection limit for CPM was 1.4×10^?8 mol·L^?1. The RSD for 5 times determinations of 1.0×10^?5 mol·L^?1 CPM was 3.2%. The results of recovery test were between 96.3%–102.5%, and the RSD of recovery test (n=5) was 2.7%. In addition, eleven kinds of tertiary amines‐Ru(bpy)₃²⁺ systems were investigated in the absence and presence of SDBS. The results showed that the enhancement of SDBS on ECL intensity of tertiary amines‐Ru(bpy)₃²⁺ systems was universal.     

Application of β-cyclodextrin in polymeric solid phase for separation and determination of lead in different environmental matrices

Immobilization of β-cyclodextrin on Dowex resin as an insoluble polymeric matrix by covalent bond presents a new solid-phase medium for preconcentration of Pb (II) at trace level in environmental samples prior to its flame atomic absorption spectrometric determination. The method is based on the sorption of lead after passing on modified Dowex sorbent in a column. The effect of several parameters such as pH, flow rate of sample, eluent kind and volume was investigated. The sorption capacity of the matrix has been found to be 0.4996?mg?g^?1 of adsorbent with the preconcentration factor of 250 for Pb (II). Nitric acid (3 M) as an eluent was sufficient to obtain quantitative recovery (>95%) for Pb (II). The optimum flow rate was 10?ml?min ^?1. The calibration curve was linear in the range of (3–250?ng?mL^?1) with a correlation coefficient of 0.9995. The limit of detection (LOD) based on three times the standard deviation of the blank was 1.37?ng?mL^?1. The relative standard deviation (RSD) for determination of 10?ng?mL^?1 and 100?ngmL^?1 of Pb (II) was 3.00 % and 0.58 % (n?=?10), respectively. The method was successfully applied to determination of lead in some environmental samples such as tap water, river water, soil and rice.     

Assay of mixtures of chlorpheniramine maleate,pyrilamine meleate and phenylpropanolamine hydrochloride in cold-allergy tablets by difference spectrophotometry

Mixtures of chlorpheniramine maleate (CPM) and phenylpropanolamine hydrochloride (PPA), with and without pyrilamine maleate (PRM), are assayed by u.v. difference spectrophotometry without prior separation. The spectra for CPM and PRM in solutions at pH 1 and pH 6 show differences whereas the spectra for PPA remain the same at pH 1 and 6. For PPA, quantitation is based on the spectral change on oxidation to benzaldehyde with metaperiodate; this oxidation does not affect CPM and PRM. Calibration plots are linear for 6.7–99.9 μg ml^?1 CPM (r = 0.9992), 12.7–50.6 μg ml^?1 PRM (r = 0.9997) and 25–115.3 μg ml^?1 PPA (r = 0.9980) in the presence of one another. Average recoveries (± RSD) from simulated PPA/CPM tablets were: PPA, 98.4 ± 0.4% (without PRM, n = 3), 99.8 ± 0.4% (with PRM, n = 5); CPM, 99.3 ± 0.6% (without PRM, n = 3), 99.2 ± 0.4% (with PRM, n = 5); and PRM, 99.5 ± 0.2% (in PPA/CPM/PRM tablets, n = 5). The method was successfully applied to commercial cold-allergy tablets containing these compounds.     

ANIONIC COORDINATION COMPLEXES OF Mo AND W WHICH CRYSTALLIZE FROM LIQUID CLATHRATE MEDIA WITH OXONIUM ION-CROWN ETHER CATIONS

Abstract

The complexes [H₃O⁺·18-crown-6][MoOCl₄(H₂O)^?], 1, and [H₂O·aza-18-crown-6·(H⁺)] [MoOCl₄(H₂O)^?], 3, were synthesized from a mixture of Mo(CO)₆, HCl(g), H₂O and either 18-crown-6 for 1 or mono-aza-18-crown-6 for 3, in toluene. For complex 4, [H₂O·aza-18-crown-6·(H⁺)]₂[WOCl₄(H₂O)^?][Cl^?], reaction conditions were as for 3 except W(CO)₆ was used in place of Mo(CO)₆. Similarly, for complex 2, [H₃O⁺·18-crown-6][WOBr₄(H₂O)^?], W(CO)₆ and HBr were used in the reaction mixture. These reactions were promoted by UV radiation and formed liquid clathrates almost immediately upon reaction. X-ray crystal structures were performed on each compound. Complex 1 crystallizes in the triclinic space group P/i with a = 10.206(1), b = 10.486(1), c = 11.701(1) Å, α = 71.11(1), β = 74.60(1), γ = 75.08(1)°, and D _c = 1.649 g cm^?3 for Z = 2. Refinement based on 3925 observed reflections led to a final R value of 0.078. Complex 2 crystallizes in the monoclinic space group P2₁/c with a = 9.710(1), b = 19.824(1), c = 12.399(1) Å, β = 104.58(1)°, and D _c = 2.369 g cm^?3 for Z = 4. Refinement based on 2008 observed reflections led to a final R value of 0.090. Complex 3 crystallizes in the orthorhombic space group Pnmn with a = 16.927(1), b = 12.226(1), c = 11.167(1) Å, and D _c = 1.598 g cm^?3 for Z = 4. Refinement based on 1486 observed reflections led to a final R value of 0.040. Complex 4 crystallizes in the monoclinic space group C2/m with a = 11.761(2), b = 12.096(2), c = 14.966(1) Å, β = 132.91(1)°, and D _c = 1.502 g cm^?3 for Z = 4. Refinement based on 2021 observed reflections led to a final R value of 0.051. In all cases the metal coordination sphere was essentially octahedral with the water ligand trans to the oxo species.     

Electrophoretic and spectrophotometric determination of triiodides of sulfur-containing organic cations

Trimethylsulfonium triiodide (I) and p-xylylene-bis-(tetrahydrothiophenium) triiodide (II) were identified and determined by capillary electrophoresis with the resolution R _s = 4.86 using an unmodified quartz capillary. The procedure ensures the determination of sulfur-containing organic compounds in a concentration range of 1.0 × 10^?5–5.0 × 10^?4 M RSD ≤ 5%). The high stability of trimethylsulfonium triiodide and p-xylylene-bis-(tetrahydrothiophenium) triiodide in chloroform and acetonitrile solutions was found by spectrophotometry. A procedure was proposed for the spectrophotometric determination of compounds I and II as ion associates of sulfur-containing cations with a sulfophthalein dye, Bromocresol Purple (c _min (I) = 1.32 × 10^?5 M, c _min (II) = 7.1 × 10^?6 M, RSD = 5%), and by the characteristic absorption of the triiodide anion in acetonitrile (c _min (I) = 3.18 × 10^?6 M, c _min (II) = 2.76 × 10^?6 M, RSD <-3%).     

Simultaneous determination of five triterpenic acids in four Corydalis herb medicines by reversed-phase high performance liquid chromatography–fluorescence-mass spectrometer (RP-HPLC–FLD-MS) based on pre-column derivatization

A rapid and sensitive reversed-phase high performance liquid chromatography– fluorescence-mass spectrometer (RP-HPLC–FLD-MS) method based on pre-column derivatization using 2-(5-benzoacridine)ethyl-p-toluenesulfonate (BAETS) as labelling reagent has been developed for simultaneous determination of five triterpenic acids (asiatic acid (AA), maslinic acid (MA), corosolic acid (CA), oleanolic acid (OA), and betulinic acid (BA). The presented method was validated for linearity (correlation coefficient R² > 0.9994), precision (RSD 2.1%–3.9%) and reproducibility (RSD 0.01%–2.1%). The limits of detection (LODs) and the limits of quantitation LOQs were within the range of 0.71–1.02 ng mL^?1 and 2.28–3.24 ng mL^?1, respectively. The proposed method was successfully applied to simultaneously determine five triterpenic acids of four Corydalis plants and showed satisfactory reproducibility and credibility. Moreover, several main parameters affecting extraction procedure and derivatization efficiency were investigated by response surface methodology (RSM), respectively. Triterpenic acid content in four Corydalis plants was measured according to the established method and the results indicated that triterpenic acid contents were various in different organs and herbs.     

Highly sensitive ion preconcentration method based on flow sorbent extraction using multiwall carbon nanotubes

In this work a solid phase on-line uranium ion preconcentration system coupled with spectrophotometry has been developed. The method is based on uranyl ion preconcentration at pH 3.75 onto multiwall carbon nanotubes treated with HNO₃. After preconcentration, the uranyl ions are eluted with 0.32?mol?L^?1HCl followed by reaction with 3,6-bis[(2-arsonophenyl)-azo]-4,5-dihydroxy-2,7-naphthalendisulfonic acid 0.08%[w/v] (Arsenazo III), which had maximum monitored absorbance of 650?nm. Effects of the pertinent experimental parameters on the system were investigated by means of 2^6?2 fractional factorial design, while optimization was carried out using the Doehlert matrix. Under optimized conditions, detection and quantification limits were found to be 0.21 and 0.7?µg?L^?1, respectively. The analytical curve ranged from 5 to 150?µg?L^?1 (r?=?0.998), while the relative standard deviations (RSD) were 3.27 and 2.56% for the respective uranium concentrations of 10 and 100?µg?L^?1 (n?=?10). The features obtained for the on-line preconcentration system were: preconcentration factor of 228, concentration efficiency of 57?min^?1, consumption index of 0.13?mL and sample throughput of 15?h^?1. In order to assess the accuracy of the proposed method, addition and recovery studies were carried out on spring water samples from different sources and synthetic seawater with satisfactory results ranging from 94.85 up to 103.65%.     

Flow‐Injection Chemiluminescence Analysis of Cloperastione Hydrochloride

Abstract

A new chemiluminescence (CL) reaction was observed when cloperastine hydrochloride was injected into the reaction mixture after the CL reaction of Ce(IV) and sodium sulfite finished. A new flow injection CL method for the determination of cloperastine hydrochloride was established based on the CL reaction. The relative standard deviation (RSD) for the determination of cloperastine hydrochloride was 1.3% (n=11, c=1.0×10^?6 g/mL). The CL intensity responded linearly to the concentration of cloperastine hydrochloride in the range 2.0×10^?7～2.0×10^?5 g/mL (r=0.9962). The detection limit was 5×10^?8 g/mL cloperastine hydrochloride. The method had been applied to the determination of cloperastine hydrochloride in tablets with satisfactory results.